1. Field of the Invention
The present invention relates to an imaging device and a focusing method comprising a focus function enabling fast focusing on an object.
2. Description of the Related Art
In conventional imaging apparatus such as digital cameras, contrast auto-focusing (AF) processing is generally known as a method for performing auto-focusing on an object.
Contrast AF processing focuses by driving a focus lens within a drivable range from lens edge to lens edge, detecting the contrast component from an imaging signal which is the CCD output at this time and interpreting this waveform, namely, adjusting the lens into a lens position where the high-frequency component is the largest.
Additionally, an invention which is an automatic focusing device for cameras is disclosed in Japanese Laid-Open (Kokai) Patent Publication No. 2003-140027. Specifically, in contrast AF processing, power consumption required for the emission of AF fill light can be reduced when irradiating AF fill light onto an object to heighten the contrast of the object by emitting the AF fill light only when the image pickup lens moves a predetermined distance rather than emitting continuously during the movement duration of the image pickup lens.
However, according to the conventional imaging apparatus, since contrast is detected by moving the focus lens from lens edge to lens edge, AF processing takes time. This is problematic in that photo opportunities are lost when a user wishes to photograph an object quickly, such as at a decisive moment.